The Northern Map Turtle’s carapace (top shell) is olive or brown-black with a pattern of light yellow lines which often fade as turtles mature. These lines tend to look like the turtle has a map on their back, giving them their Map Turtle name. Their plastron (bottom shell) is light yellow or cream in colour. Their head, neck, and limbs have long green-yellow stripes. Identifying features are the serrated edges of their carapace along with the map detail, and the yellow lines on their head and limbs. Females are much larger than males, with carapace lengths of up to 25 cm, while males are generally around 14 cm. Males average only about 20% of the mass of females, and relative to body size they have thicker and longer tails than females.
The Northern Map Turtle’s diet largely consists of molluscs, but also includes crayfish and aquatic insect larvae. Males and females actually have different diets- females mainly consume larger molluscs, whereas males feed more on aquatic insects, crayfish, and smaller molluscs. Northern Map Turtles generally prefer lake habitats where there are greater concentrations of their prey.
Biology and Behaviour:
Like other turtle species, Northern Map Turtles have low juvenile success and long lived adults. Females are late to get to sexual maturity, which is approximately 12 years. Northern Map Turtles will emerge from hibernation in early spring and make their way to their mating grounds. In Canada, nesting begins early to mid June. Females can lay two clutches in one year, the second one occurring in August or September where hatchlings will overwinter underground until emerging in the spring. Female Northern Map Turtles will generally nest close to water, either along the shores of a lake or river in sand, clay, or gravel substrate. They will lay 10-16 eggs, larger and older females are able to lay more eggs than younger females. Eggs remain in the nest to incubate until early August, where they emerge and head to the nearest water body.
Northern Map Turtles will head to their hibernation sites once the weather starts to turn cool. They will either hibernate individually or in groups, depending on the hibernating site characteristics and number of turtles that may use the same site. Northern Map Turtles will generally overwinter in shallow water under a thick ice layer. Hibernation can be dangerous since they cannot easily tolerate low oxygen levels or freezing, so the conditions must be ideal.
Known predators of adults, juveniles and eggs include Mink, Raccoon, Red Fox and Coyotes. Hatchlings also have the same predators, but they also include Green Frogs, large fish, Snapping Turtles, American Bullfrogs, Gulls, Terns and Herons.
Northern Map Turtles are often confused with Midland Painted Turtles. Both species have yellow striping, but Map turtles have the distinct yellow triangles near their eyes region and no red striping on their shell or body. They also have very different shells- Northern Map Turtle shells are typically lighter brown with serrated edges and Painted Turtles shells are darker with no yellow lines.
Conservation and recovery strategies:
Effective conservation and recovery strategies would involve protecting remaining undeveloped shoreline habitat through stewardship or land acquisition, and rehabilitating as much shoreline as possible. Boating speed limits should be reduced, as well as horsepower allowed in lakes and rivers that support Northern Map Turtle populations. Better regulation of mitigation strategies in commercial fisheries should be put in place to reduce turtle bycatch, and increased signage warning drivers to watch for turtles, and reduced speed limits in hotspots for road kill.
While the Northern Map Turtle is not being protected at the government level, there are many organizations that have stepped up to help. The Ontario Turtle Conservation Centre in Peterborough will incubate eggs and rehabilitate injured turtles, and here at The Land Between we have staff and volunteers that are out on busy roads during the spring and summer to ensure that all turtle species can safely nest and cross roads. We even have the ability to excavate turtle nests for incubation and release once they have hatched.
Bennett, A.M., M. Keevil, and J. Litzgus. 2009. Demographic differences among populations of Northern Map Turtles (Graptemys geographica) in intact and fragmented sites. Canadian Journal of Zoology 87:1147-1157.
Nagle, R., C. Lutz, and A. Pyle. 2004. Overwintering in the nest by hatchling map turtles (Graptemys geographica). Canadian Journal of Zoology 82: 1211-1218.
Bulté, G., Carriere, M.A. and Blouin-Demers, G., 2010. Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica). Aquatic Conservation: Marine and Freshwater Ecosystems, 20(1), pp.31-38.
Midwood, J.D., Cairns, N.A., Stoot, L.J., Cooke, S.J. and Blouin‐Demers, G., 2015. Bycatch mortality can cause extirpation in four freshwater turtle species. Aquatic Conservation: Marine and Freshwater Ecosystems, 25(1), pp.71-80.
Environment Canada. 2016. Management Plan for the Northern Map Turtle (Graptemys geographica) in Canada [Proposed]. Species at Risk Act Management Plan Series. Environment Canada, Ottawa. iv + 45 pp. https://www.registrelep-sararegistry.gc.ca/virtual_sara/files/plans/mp_northern_map_turtle_e_proposed.pdf
COSEWIC. 2012. Northern map turtle (Graptemys geographica): COSEWIC assessment and status report 2012. Committee on the Status of Endangered Wildlife in Canada. Ottawa. Retrieved from https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/northern-map-turtle-2012.html
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